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Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
Peer to peer
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Peer to peer

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  • 1. Peer-to-Peer System Raviteja Adusumalli ali@sics.se 1
  • 2. Definition• What is a distributed system? ”You know you have a distributed system when the crash of a computer you have never heard of stops you from getting any work done.” Leslie Lamport We counteract this definition! ali@sics.se 2
  • 3. Distributed Systems• Example of distributed systems: – File systems Frequently, an organization – Web servers stores all its files on a centralized distributed file server – Mail servers If it fails, no one can access their – Databases files The central mail server crashes, no one can read their Webb servers often become email! overloaded and fail ali@sics.se 3
  • 4. Our effort• Build on an 30-year old idea• Arpanet, the precursor of Internet, was built for: – Military survivability • If some part stops working, the rest should continue to function• Internet has been quite successful so far… – No fail-stop yet• But the effort stopped here… ali@sics.se 4
  • 5. Peer-to-Peer System• We want to build – Services – Servers – Applications• That are self-managed• Achieved by peer-to-peer techniques! ali@sics.se 5
  • 6. Peer-to-Peer Middleware• After several years of research – Built a middleware: DKS• Provides: – Routing services – Directory services – Name-based messaging (multicast/publish/subscribe) ali@sics.se 6
  • 7. Peer-to-Peer System• DKS is self-managing• Automatic managent: – Adding servers/resources – Removing servers/resources – Crash of servers/resources – Load balancing of data/nodes – Security ali@sics.se 7
  • 8. Peer-to-Peer?• How is it different from: – KaZaa – Napster – Gnutella – Skype• These are so called unstructured p2p systems – Limited applicability (file sharing) – Inefficient (wastes bandwidth)• Our focus is on structured p2p systems – Chord/CAN/Pastry (USA) – DKS/P-Grid (Europe) ali@sics.se 8
  • 9. What can we do with DKS?• Three concrete applications: – P2P Web server – P2P Backup – P2P File system ali@sics.se 9
  • 10. P2P Web• Works like an Publish your web pages ordinary web server• Differences: – It is distributed – Automatic data Gets stored on the DKSStore a copy here replication 15 0 Store it here 1 – Load-balancing 14 15 1 2 of users 13 13 3 4 12 4• Too much load 5 – Add another 11 5 server Store a new copy here 10 6 9 7 8 ali@sics.se 10
  • 11. P2P Backup• Initialization – Install a client on your computer – Decide on amount of space to share – Choose files for backup• Regular backup – Data is encrypted – Always accessible ali@sics.se 11
  • 12. Conclusion• Structured Peer-to-Peer system – Self-organizing • Automatic fault-tolerance • Automatic addition of nodes/resources • Automatic removal of nodes/resources • Automatic load-balancing• Many interesting applications – File systems – Backup – Web – M.m.• Cost-saving for companies – Save money on administration ali@sics.se 12

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